半干旱黄土高原生物结皮处理下集水造林的初步研究(英文)

集水措施是干旱半干旱地区解决因降雨少且季节间分配不均带来的水资源短缺的主要措施之一,有关微集水区防渗处理材料及其防渗效果的研究也已广泛开展。本文通过5 年(1992-1996)的野外试验对半干旱黄土高原微集水系统生物结皮覆盖对造林的影响进行了研究。结果表明,结皮接种3 年后,集水区表面大部分为结皮所覆盖,其集水功能已经部分地表现出来。在春季3 个典型时段内浅层土壤含水量与对照相比显著提高(0.05 水平),1m 土层内春季月均含水量均比对照提高了0.9%–6.04%。同时在研究期末(1996 年)结皮处理的样地内树木个体的树高(H)、胸径(DBH)和地径(DGL)均较对照有显著提高(0.05 水平),提高幅度分别为22.38%、17.34%和20.49%。作为一种生物防渗材料,生物结皮具有无污染、自我繁殖、使用期长和投入小等特点,因此很可以作为西部大开发中植被恢复的主要集水材料,进一步的工作应放在干旱环境下当地适宜结皮种类的选择及其快速繁殖技术上。     

Seasonal changes of understorey herbage yield in relation to light intensity and soil moisture content in a Pinus pinaster plantation

The relationship of understorey herbage yield with light intensity and soil moisture content was investigated in a 20-year-old Pinus pinaster plantation in Kilkis of Macedonia, northern Greece, in three seasons (fall, winter and spring). The plantation was thinned at three density levels, high, medium and low (2500, 1750 and 1000 trees/ha respectively) and it was seeded with Dactylis glomerata. In addition, two fertilization levels (0 and 110 N+150 P₂O₅ kg/ha) and grazing intensity levels (0 and 0.8 sheep/ha/yr) were applied in a split-split plot experimental design. It was found that herbage yield was highest in the ungrazed and fertilized low tree density stands in all seasons. In the medium tree density stand, although light was lacking, fertilized plots produced higher herbage yield as compared to unfertilized low tree density stands while fertilization is of no use in close stands if herbage production is the goal. Animals seemed to prefer fertilized and medium density stands. Third degree polynomial equations were the best to explain herbage variation through the seasons both in fertilized and unfertilized plots.     

Microclimate and soil moisture effects of three intercrops on the rows of a newly-planted intercropped plantation

Trees are grown in intercropping systems for a variety of purposes including wood products, fuelwood, fruit, forage or conservation purposes. No matter what end use, different tree/crop combinations interact differently resulting in differential growth rates of the trees during establishment. Preliminary work has shown that seedling growth and survival of trees are related to their intercrop and the results of this study help to explain these findings. Soil water potential, soil and air temperature, relative humidity, windspeed, and light (photosynthetic photon flux density — PPFD) were measured throughout the growing season in the clean-weeded treerows within crops of corn, soybeans and winter wheat. Crop height and biomass were also measured. This study was conducted during the 1992 growing season which was unusually cool and wet from mid June into the winter. The growth of winter wheat, measured by crop height and above-ground biomass, was earlier in the season than that of soybeans and corn, and this pattern affected the environmental conditions in the tree rows. Soil water potential was affected with associated effects on soil temperature (in combination with other factors). Crop height drastically reduced windspeed in the corn treatment from July through winter, also affecting PPFD and soil temperature later in the year. Although many microclimate differences were relatively small, data from subsequent years as well as associated soil moisture studies and additional years will help to further elucidate these relationships.     

Estimating root mass in young hybrid poplar trees using the electrical capacitance method

A preliminary field study was conducted on root mass of young hybrid polar trees (Populus deltoides x P. nigra) using the electrical capacitance method. The objective of this study was to develop a simple calibration relationship that would enable root mass (fresh or dry) to be estimated for young hybrid poplar trees grown in mineral soils using simple, non-intrusive measurements of electrical capacitance. For first-year potted saplings (n = 33), strong linear and positive correlations were found between both root dry mass (adjusted r² = 0.895, P<0.001) and root fresh mass (adjusted r² = 0.866, P<0.001) and root electrical capacitance for the particular DN hybrid poplar clone studied. When augmented with data from third-year DN saplings grown in a more harsh landfill environment, a somewhat less strong curvilinear relationship was indicated with root dry mass (adjusted r² = 0.780, P<0.001, n = 50). This rapid field method may be capable of providing adequate estimates of root mass for young trees in a variety of applications, such as afforestation, agroforestry or phytoremediation studies. This revised version was published online in June 2006 with corrections to the Cover Date.     

Influence of nursery soil amendments on water relations,root architectural development,and field performance of Douglas-fir transplants

This experiment evaluated the influence of manure, peat, and vermiculite incorporated at low and high rates (0.0118 and 0.0236 m³/m²) and under two soil moisture regimes on Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedling (1+0 for 1+1) xylem water potential (_xylem), whole-plant growth, root architectural development, and subsequent field performance under fertilized and non-fertilized conditions. Trends in soil moisture retention were observed (high manure > high peat > control) but there were no differences in _xylem. Root length in the wetter soil moisture experiment was initially (three months) greatest for seedlings in high vermiculite and least in high manure but there were no differences among treatments at lifting (eight months). Mean height was greatest for seedlings grown in vermiculite and peat (wetter nursery experiment) after two field seasons. Field fertilization (35 g/seedling) with controlled-release fertilizer in the planting hole stimulated height growth initially, but decreased height and diameter growth during the second growing season. Dramatic improvements associated with the use of nursery soil amendments were not realized, but the failure to identify negative effects, a potential reduction in disease incidence, and improvement of nursery soil physical and chemical properties may justify their use.     

顺德地区不同森林改造区土壤水分—物理特性研究

森林土壤水分—物理特性研究是森林生态系统研究的一项重要内容。土壤是固相、液相、气相三相态的综合体。其中土壤水分是最活跃的因素,是联系地表水和地下水的纽带,是陆地植物赖以生存的源泉[1]。在对顺德市调查和论证的基础上,2000年开始实施“青山工程”森林改造,将完成全市1181 7hm2林分改造,广泛应用乡土阔叶树种,恢复“多树种、多层次、多色彩、多功能”的地带性植被群落,充分发挥森林的生态功能,达到改善城市环境质量、提高城市文化含量、提升城市形象的目的,为此就顺德地区不同森林改造区土壤水分—物理特性进行了分析和研究。1　研…     

异叶爬山虎光合生理特性的研究

应用英国PPS公司生产的CIRAS-2型光合作用系统,在不同土壤水分条件下测定了2年生爬山虎苗木叶片生理参数的光响应特性。结果表明:爬山虎对光照强度有一定的适应范围,具有较强的抗旱性而不适应高土壤水分环境,是适用于干旱瘠薄荒山绿化的优良藤本树种。     

太行山北部中山幼林地土壤水分的研究

以太行山北部山西五台山中山地区幼林地土壤为研究对象，在阳坡、阴坡和半阳坡三种代表性立地上，从土壤水势、水容量等持水特性和土壤水分季节变化角度，并结合树木抗旱性和生长，研究了该地区土壤水分供应状况及其与造林成活和幼林生长的关系。研究表明，土壤有效水范围为－０．３－－２０ｂａｒ，正常生长水在－０．３－－３ｂａｒ，轻胁迫水－３－－１０ｂａｒ，中胁迫水为－１０－－２０ｂａｒ；土壤持水特性和有效水范围以阳坡最小，半阳坡最大；土壤自然含水率和有效水含量随降水而呈明显的季节变化特征，阴坡全年土壤含水率高，有效水充足，造林成活率高，幼林生长快，半阳坡和阳坡土壤含水率低，有效水较少，林木易于受旱，需选择抗旱树种，采取抗旱造林措施；整地可明显改善土壤水分状况，是抗旱造林和促进幼林生长的良好措施。     

小径木白桦锯材不同加热方式下含水率的变化

讨论小径木白桦锯材在连续加热和间歇加热方式下含水率的变化规律.结果表明:小径木白桦锯材的干燥速率在含水率15%以后明显降低,前期干燥过程锯材的干燥速率比后期的高2～3倍;间歇加热方式有利于内部水分向外扩散,间歇时间对干燥速率的影响很小;干燥过程中锯材厚度方向上的含水率梯度呈不对称分布,这与小径木的心材占较大比例有一定关系;间歇加热减少了锯材内含水率梯度的变化值,同时减少了应力的产生,从而提高了干燥质量.     

玉米淀粉改性UF树脂胶合高含水率单板

采用半酯化的玉米淀粉与脲醛树脂(UF)共聚改性,探讨加入量、脲醛树脂的量比、混合比、热压条件等对胶液的黏度、稳定性、固化时间及胶合质量的影响.结果表明:当单板含水率提高到16%～18%时,用改性UF树脂生产的多层胶合板,其物理力学性能指标达到GB/T 9846.1～12-88中Ⅱ类胶合板的要求,并大幅度地降低了胶合板的制造成本.